Unit 0: Psychology Research Methods: Quick Reference Notes (Qualitative/Quantitative, Case Studies, Sampling, Reliability, Validity, Bias)

Qualitative: descriptive, focuses on feelings, observations, and descriptions; typically non-numeric.
Quantitative: uses numerical data; can be analyzed statistically; converts some qualitative data to quantitative via operational definitions.
Operational definition: method to turn a qualitative concept into a measurable quantity, e.g., happiness on a scale from $1$ to $10$ ; example in class: happiness rated on a scale to quantify mood.
Example from transcript: qualitative observation about feelings; then added a numeric value on a scale to create quantitative data.

Case study: descriptive observation technique using interviews; can have two meanings: (1) published research documenting a case, (2) a student-written case study report.
Phineas Gage: railroad worker, suffered frontal lobe injury; personality change after injury; case study used to illustrate frontal lobe functions and personality changes.
Frontal lobe: front of brain; involved in decision making and personality; injuries here can alter behavior.
Ethics in case studies: maintain anonymity; do not reveal identifying information; present information responsibly.

Start from observations (descriptive notes) and convert into a short essay (about one page).
Bottom-part task: summarize observations coherently, noting general characteristics and abnormal features when present.
Two key modes of writing in class: case study write-ups (book-report style) vs. actual experiments; distinguish whether the activity is observation-based or an experiment.

Two main elements: If-Then statements (hypotheses) and present-out statements (predictions or conclusions stated in present tense).
Focus on experiments and correlation analyses in class; many assignments come with existing hypotheses in published case studies, while you write a short report.
Purpose of hypothesis: guides the experiment; understanding of how observations lead to testable predictions.

Population: the entire group you want to study.
Sample: a subset of the population actually studied.
Representative sample: a sample that reflects the characteristics of the population (e.g., mix of genders, ages, ethnicities).
Random sample: selection without bias; helps reduce sampling bias.
Example considerations: age range (e.g., $14-18$ ), whether the sample represents all groups in the population; freshman exclusion can make a sample non-representative.

Reliability (repeatability): ability to obtain the same results when the study is repeated with the same methods.
Validity: whether the test actually measures what it intends to measure; a valid test assesses the intended content or construct.
Practical examples: an AP psychology test is considered valid for AP psychology if it measures AP psychology content; a generic physics test for AP US History would be invalid for AP psychology.
Bias in research: researchers’ expectations can influence results (e.g., hindsight bias, overconfidence); avoid allowing expectations to color interpretations.
Hindsight bias: after outcomes are known, people think they could have predicted them (hindsight is $20/20$ ).

Anonymity and privacy: protect identities of participants; use general descriptions (e.g., “the subject” or “the participant”) rather than names.
Privacy and confidentiality: avoid disclosing identifying information; ensure ethical handling of data.
Ethical distinctions between case studies and experiments: both require careful, ethical reporting and protection of participant information.

Descriptive vs descriptive-qualitative data; qualitative data can be turned into quantitative data via an operational definition.
Case study involves interviews and notes compiled into a readable form; reliability and ethics matter.
Population vs sample; representative sample vs random sample; bias reduction through randomization.
Reliability, validity, and bias: essential checks for any research design; aim for high validity and reliable replication.
Hypothesis development: If-Then statements; predictive statements in present-tense form;
Phineas Gage as a historical case illustrating brain-behavior links and frontal lobe functions.
Ethical reporting practices and the importance of anonymity in written work.